ANNALS OF SCIENCE BUTTER.FLY LESSONS Insects and toads respond to global warming. BY ELIZABETH KOLBER.T P olygonia c-album, generally known as the comma butterfly, spends most of its life pretending to be something else. In its larval, or caterpillar, stage, it has a chalky stripe down its back which makes it look uncannily like a bird drop- ping. As an adult, with wings folded, it is practically indistinguishable from a dead leaf. The comma gets its name from a tiny white mark shaped like the letter "è' on its underside. Even this is thought to be part of its camouflage- an ersatz rip of the sort that leaves get when they are particularly old and tatty. The comma is a European butterfly- its American cousins are the hop mer- chant and the question mark-and it can be found in France, where it is known as Ie Robert-Ie-Diable; Germany, where it is called der C-Falter; and the Netherlands, where it is gehakkelde au- relia. The comma reaches the north- ern edge of its distribution in Britain. This is unremarkable-many Euro- pean butterflies come to the end of their range in England-but from a scientific standpoint fortunate. The English have been watching and collecting butterflies for centu- ries-some of the specimens in the British Natural History Museum date back to the seventeen-hundreds-and in the Victorian era passion for the hobby was such that even many small towns supported their own entomolog- ical societies. In the nineteen-sixties, Britain's Biological Records Centre decided to marshal this enthusiasm for a project called the Lepidoptera Dis- tribution Maps Scheme, whose aim was to chart precisely where each of the country's fifty-nine native spe- cies could-and could not-be found. More than two thousand butterfly en- thusiasts participated, and in 1984 the results were collated into a hundred- and-fifty-eight-page adas. Every spe- cies got its own map, with black dots 32 THE NEW YORKER, JANUARY 9, 2006 showing where it had been sighted. On the map for Polygonia c-album, the comma's range was shown to extend from the south coast of England up to Liverpool in the west and N or- folk in the east. Almost immediately, the map became out of date; in the years that followed, hobbyists kept finding the comma in new areas. By I I J C;, J. " ' " " -- ( the late nineteen-nineties, the butter- fly was frequently being sighted in the north of England, near Durham. By now, it is established in southern Scot- land, and has been sighted as far up as the Highlands. The rate of the com- ma's expansion-some fifty miles per decade-was described by the authors of the most recent butterfly atlas as " k bl " remar a e. Chris Thomas is a biologist at the University ofY ork who studies lepi- doptera. He is tall and rangy, with an Ethan Hawke-style goatee and an ami- ably harried manner. The day I met him, he had just returned from looking for butterflies in Wales, and the first thing he said to me when I got into his car was please not to mind the smell of wet socks. A few years ago, Thomas, his wife, their two sets of twins, an Irish wolfhound, a pony, some rabbits, two cats, and several chickens moved into an old farmhouse in the village ofWis- tow, in the Vale ofY ork. The Univer- sity ofY ork has an array of thermostatic chambers where commas are raised under temperature-controlled condi- tions, fed carefully monitored diets, and , .. -'!. - ;wg ,- I D" (/I . .... , 15' ) - .'1d , ..... - l )j :8 I'B I = I B ' measured on a near-constant basis, but, in the spirit of British amateur- ism, Thomas decided to turn his own back yard into a field lab. He scattered wildflower seeds he had collected from nearby meadows and ditches, planted nearly seven hundred trees, and waited æ for the butterflies to show up. When I V) visited the place in midsummer, the wildflowers were in bloom and the